In order for a turbine to produce shaft power, steam must pass through both the nozzle and bucket flow passages. Steam bypassing either the nozzles or the buckets due to inter-stage leakage, tip leakage, packing leakage, and other leakage flows are concerns in the turbo-machinery industry given that they do not produce power. Moreover, such leakage flows also may disrupt the flow through the nozzles and buckets so as to decrease turbine shaft output and directly impact overall turbine performance and efficiency. These leakage flows generally are caused by increased clearances between the rotating and the stationary components. The increased clearances may be caused by rubbing, solid particle erosion, foreign object damage, and the like. The amount of the leakage flow is a function of the clearance area, the geometry of the leakage path, and the pressure drop across the component being bypassed.
Currently, rotor-stator gaps and other leakage flow areas are generally sealed with labyrinth type seals. Leakage through such labyrinth seals, however, still may be a significant percentage of the overall main flow even in the best of conditions. As such, even a small reduction in this leakage flow may provide an overall performance advantage.
There is a desire therefore for improved sealing mechanisms for rotating components in turbine-machinery and the like. Improving the leakage flow through such components should improve overall turbine engine performance and efficiency. Simplified manufacture and assembly of the sealing mechanisms also may be provided herein.